Drop the existing Test database, then you just need to copy the Production database using the portal or PowerShell and set the name of the newly created database as the name of the database you initially dropped.
New-AzureRmSqlDatabaseCopy -ResourceGroupName "myResourceGroup" `
-ServerName $sourceserver `
-DatabaseName "MySampleDatabase" `
-CopyResourceGroupName "myResourceGroup" `
-CopyServerName $targetserver `
-CopyDatabaseName "CopyOfMySampleDatabase"
You can also automate refreshing the development database by recreating it using Azure Automation and the following T-SQL statement.
CREATE DATABASE db_test_copy
AS COPY OF LiveProduction ( SERVICE_OBJECTIVE = 'P2' );